Converting retired players to coaches or staff using RedMC?

Has anyone tried this? And is this doable? I see that the staff spread sheet in RedMC has portrait and CFID column, and perhaps by copying/pasting the values from players spread sheet and fill in the rest of the row, it is possible to convert players into coaches?

Yes, you can afaik

Well I tried this, adding Steve Kerr to the last row of Staff(ID 742), and make him the Warrior's coach, swapping out the current coach(who happened to be Larry Drew at that time). However, it did not work properly, and after entering association mode it says the head coach is vacated, and the portrait of another coach is listed. This is very strange, anyone knows how to fix the problem?